U.S. patent number 10,028,655 [Application Number 14/625,884] was granted by the patent office on 2018-07-24 for ophthalmologic imaging apparatus and optical unit attachable to the same.
This patent grant is currently assigned to KABUSHIKI KAISHA TOPCON. The grantee listed for this patent is KABUSHIKI KAISHA TOPCON. Invention is credited to Kouta Fujii, Kenji Miyashita.
United States Patent |
10,028,655 |
Fujii , et al. |
July 24, 2018 |
Ophthalmologic imaging apparatus and optical unit attachable to the
same
Abstract
An optical system of an ophthalmologic imaging apparatus of
embodiment splits light from a first light source into measurement
light and reference light and detects interference light of
returned light of measurement light from an eye and reference
light. An image forming part forms an image based on detection
result from the optical system. The optical unit includes a lens
and joining member. The lens is locatable in an optical path of
measurement light and used for changing a focus position of
measurement light from a first site of the eye to second site. The
joining member joins an optical path from a second light source to
the optical path of measurement light. The optical unit converges
light from the second light source having been guided into the
optical path of measurement light by the joining member on an eye
fundus via the lens.
Inventors: |
Fujii; Kouta (Toda,
JP), Miyashita; Kenji (Okegawa, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOPCON |
Itabashi-ku |
N/A |
JP |
|
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Assignee: |
KABUSHIKI KAISHA TOPCON
(Itabashi-ku, JP)
|
Family
ID: |
52822076 |
Appl.
No.: |
14/625,884 |
Filed: |
February 19, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20150245765 A1 |
Sep 3, 2015 |
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Foreign Application Priority Data
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Feb 28, 2014 [JP] |
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2014-038867 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B
3/0091 (20130101); A61B 3/12 (20130101); A61B
3/14 (20130101); A61B 3/117 (20130101); A61B
3/102 (20130101); G02B 27/141 (20130101) |
Current International
Class: |
A61B
3/14 (20060101); A61B 3/10 (20060101); A61B
3/00 (20060101); A61B 3/117 (20060101); A61B
3/12 (20060101); G02B 27/14 (20060101) |
Field of
Search: |
;351/206,211,221,200,204,210,246 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2 347 701 |
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Jul 2011 |
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EP |
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2 786 698 |
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Oct 2014 |
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EP |
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63-164938 |
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Jul 1988 |
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JP |
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6-237901 |
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Aug 1994 |
|
JP |
|
09-276232 |
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Oct 1997 |
|
JP |
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10-192244 |
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Jul 1998 |
|
JP |
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10-272104 |
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Oct 1998 |
|
JP |
|
H 11-225970 |
|
Aug 1999 |
|
JP |
|
11-325849 |
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Nov 1999 |
|
JP |
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2002-139421 |
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May 2002 |
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JP |
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2004-180707 |
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Jul 2004 |
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JP |
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2006-153838 |
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Jun 2006 |
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JP |
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2007-024677 |
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Feb 2007 |
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JP |
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2007-275160 |
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Oct 2007 |
|
JP |
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2008-073099 |
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Apr 2008 |
|
JP |
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2008-259544 |
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Oct 2008 |
|
JP |
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2009-011381 |
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Jan 2009 |
|
JP |
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2011-50439 |
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Mar 2011 |
|
JP |
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2011-147609 |
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Aug 2011 |
|
JP |
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2012-223435 |
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Nov 2012 |
|
JP |
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2013-153796 |
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Aug 2013 |
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JP |
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Other References
Office Action dated Jul. 23, 2015 in United Kingdom Patent
Application No. GB1503045.5. cited by applicant .
German Office Action dated Sep. 13, 2016, issued in German Patent
Application No. 10 2015 203 443.7. cited by applicant .
An Invitation to Attend an Oral Hearing dated Oct. 30. 2017, issued
in German Patent Application No. 102015203443.7 (with English
translation). cited by applicant .
Japanese Office Action dated Jan. 9, 2018, issued in Japanese
Patent Application No. 2016-150251 (with English translation).
cited by applicant.
|
Primary Examiner: Pinkney; Dawayne A
Attorney, Agent or Firm: Oblon, McClelland, Maier &
Neustadt, L.L.P.
Claims
What is claimed is:
1. An ophthalmologic imaging apparatus comprising: an objective
lens; an optical system that splits light from a first light source
into measurement light and reference light and detects interference
light of returned light of the measurement light from an eye and
the reference light via the objective lens; an image forming part
that forms an image based on detection result from the optical
system; a fixation optical system that presents a first fixation
target to the eye via the objective lens; an optical unit
comprising a lens that is locatable in an optical path of the
measurement light and used for changing a focus position of the
measurement light from a first site of the eye to a second site and
a joining member that joins an optical path from a second light
source to the optical path of the measurement light, wherein the
optical unit converges light from the second light source having
been guided into the optical path of the measurement light by the
joining member on a fundus of the eye via the lens as a second
fixation target; and one or more external fixation light sources
that are located outside the optical unit and are arranged on a
circle centered at an optical axis of the objective lens; wherein
the optical unit is placed/removed in/from an optical path of the
measurement light between the eye and the objective lens; the
second light source comprises any of the one or more external
fixation light sources; and the lens is located in an optical path
of light from the fixation optical system.
2. The ophthalmologic imaging apparatus of claim 1, wherein the
first light source outputs light including infrared light, the
second light source outputs light including visible light, and the
joining member comprises a dichroic mirror.
3. The ophthalmologic imaging apparatus of claim 1, wherein the
optical unit comprises a relay optical system that relays an image
of the second light source to the joining member.
4. The ophthalmologic imaging apparatus of claim 1, wherein the
first site is the fundus and the second site is an anterior eye
part.
5. The ophthalmologic imaging apparatus of claim 1, wherein the
first site is an anterior eye part and the second site is the
fundus.
6. The ophthalmologic imaging apparatus of claim 1, further
comprising: a detector that detects whether or not the optical unit
is located in the optical path of the measurement light; and a
controller that executes control for converging the light from the
second light source on the fundus of the eye by the optical unit
when the detector detects that the optical unit is located in the
optical path of the measurement light.
7. The ophthalmologic imaging apparatus of claim 6, wherein the
controller executes control for presenting the fixation target by
the fixation optical system when the detector detects that the
optical unit is not located in the optical path of the measurement
light.
8. The ophthalmologic imaging apparatus of claim 4, wherein the
optical unit comprises a relay optical system that relays an image
of the second light source to the joining member.
9. The ophthalmologic imaging apparatus of claim 5, wherein the
optical unit comprises a relay optical system that relays an image
of the second light source to the joining member.
10. The ophthalmologic imaging apparatus of claim 4, further
comprising: a detector that detects whether or not the optical unit
is located in the optical path of the measurement light; and a
controller that executes control for converging the light from the
second light source on the fundus of the eye by the optical unit
when the detector detects that the optical unit is located in the
optical path of the measurement light.
11. The ophthalmologic imaging apparatus of claim 5, further
comprising: a detector that detects whether or not the optical unit
is located in the optical path of the measurement light; and a
controller that executes control for converging the light from the
second light source on the fundus of the eye by the optical unit
when the detector detects that the optical unit is located in the
optical path of the measurement light.
12. The ophthalmologic imaging apparatus of claim 3, further
comprising: a detector that detects whether or not the optical unit
is located in the optical path of the measurement light; and a
controller that executes control for converging the light from the
second light source on the fundus of the eye by the optical unit
when the detector detects that the optical unit is located in the
optical path of the measurement light.
13. An optical unit attachable to an ophthalmologic imaging
apparatus that comprises an objective lens and an optical system
that splits light from a first light source into measurement light
and reference light and detects interference light of returned
light of the measurement light from an eye and the reference light
via the objective lens and an image forming part that forms an
image based on detection result from the optical system, wherein
the optical unit is placed/removed in/from an optical path of the
measurement light between the eye and the objective lens, the
ophthalmologic imaging apparatus further comprising a fixation
optical system that presents a first fixation target to the eye via
the objective lens, and the optical unit comprising: a lens that is
used for changing a focus position of the measurement light from a
first site of the eye to a second site; and a joining member that
joins an optical path from a second light source to the optical
path of the measurement light, wherein the optical unit converges
light from the second light source having been guided into the
optical path of the measurement light by the joining member on a
fundus of the eye via the lens as a second fixation target; one or
more external fixation light sources that are located outside the
optical unit and are arranged on a circle centered at an optical
axis of the objective lens; the second light source comprises any
of the one or more external fixation light sources; and the lens is
located in an optical path of light from the fixation optical
system.
14. The optical unit of claim 13, wherein the first light source
outputs light including infrared light, the second light source
outputs light including visible light, and the joining member
comprises a dichroic mirror.
15. The optical unit of claim 13, further comprising a relay
optical system that relays an image of the second light source to
the joining member.
Description
TECHNICAL FIELD
The present invention relates to an ophthalmologic imaging
apparatus for acquiring images of an eye by means of optical
coherence tomography (OCT) and an optical unit attachable to the
same.
BACKGROUND TECHNOLOGY
In recent years, OCT that forms images expressing surface and
internal morphologies of an object by using light beam from laser
light source etc. has attracted attention. OCT is noninvasive to
human bodies unlike X-ray CT and is therefore expected to be
utilized in medical and biological fields in particular. For
example, apparatuses that form images of fundus, cornea etc. are in
a practical stage in ophthalmology.
An apparatus disclosed in Patent Document 1 uses a technique
so-called "Fourier Domain OCT." Specifically, the apparatus
irradiates low-coherence light beam to an object, superposes
reflected light thereof and reference light to generate
interference light, acquires spectral intensity distribution of the
interference light and executes Fourier transform on it, thereby
imaging morphology of the object along a depth direction
(z-direction). Further, the apparatus is provided with a galvano
mirror for scanning light beam (measurement light) in one direction
(x-direction) perpendicular to the z-direction and forms an image
of a desired measurement target region of the object. An image
formed by this apparatus is a two-dimensional cross-sectional image
in the depth direction (z-direction) along the scanning direction
(x-direction) of the light beam. The technique of this type is also
called Spectral Domain.
Patent Document 2 discloses a technique of scanning measurement
light in horizontal and vertical directions (x-direction and
y-direction) to form multiple two-dimensional cross-sectional
images along the horizontal direction and of acquiring and imaging
three-dimensional cross-sectional information of a measured area
based on the cross-sectional images. examples of such
three-dimensional imaging include a method of arranging and
displaying cross-sectional images along the vertical direction
(referred to as stack data etc.), a method of executing rendering
on volume data (voxel data) based on stack data to form a
three-dimensional image.
Patent Documents 3 and 4 disclose other types of OCT. Patent
Document 3 describes an OCT apparatus that images morphology of an
object by scanning wavelength of light irradiated to an object
(wavelength sweeping), detecting interference light obtained by
superposing reflected lights of respective wavelengths on reference
light to acquire spectral intensity distribution and executing
Fourier transform on it. Such an OCT is called Swept Source type.
The Swept Source type is a kind of the Fourier Domain type.
Patent Document 4 describes an OCT apparatus that irradiates light
having a certain beam diameter to an object and analyzes components
of interference light obtained by superposing reflected light
thereof and reference light, thereby forming an image of the object
in a cross-section orthogonal to travelling direction of the light.
Such an OCT apparatus is called full-field type or en-face
type.
Patent Document 5 discloses an application of OCT to ophthalmology.
Before OCT was applied, retinal cameras, slit lamp microscopes,
scanning laser ophthalmoscopes (SLO) etc. were used for observing
an eye (see Patent Documents 6, 7 and 8 for example). A retinal
camera photographs a fundus by projecting illumination light on an
eye and receiving reflected light from the fundus. A slit lamp
microscope obtains a cross-sectional image of a cornea by cutting
off light section of the cornea by using slit light. An SLO images
morphology of retinal surface by scanning a fundus with laser light
and detecting reflected light with a highly sensitive imaging
element such as a photomultiplier.
As described above, OCT is superior relative to retinal cameras
etc. in that high-definition image may be obtained, further in that
cross-sectional image and three-dimensional image may be obtained,
etc.
Thus, ophthalmologic imaging apparatuses using OCT may be used for
observation of various sites of an eye and is capable of acquiring
high-definition images; therefore, OCT has been applied to
diagnoses of various ophthalmologic disorders. Now, ophthalmologic
imaging apparatuses capable of performing OCT measurement of both
fundus and anterior eye part are sometimes used for observing
various sites of eyes. An Attachment (adopter or optical unit) for
changing focus position of measurement light from fundus to
anterior eye part is selectively applied to such an ophthalmologic
imaging apparatus (see Patent Document 9). This attachment includes
a lens having predetermined refractive power.
PRIOR ART DOCUMENTS
Patent Documents
[Patent Document 1] Japanese Laid-open Patent Publication No.
H11-325849
[Patent Document 2] Japanese Laid-open Patent Publication No.
2002-139421
[Patent Document 3] Japanese Laid-open Patent Publication No.
2007-24677
[Patent Document 4] Japanese Laid-open Patent Publication No.
2006-153838
[Patent Document 5] Japanese Laid-open Patent Publication No.
2008-73099
[Patent Document 6] Japanese Laid-open Patent Publication No.
H09-276232
[Patent Document 7] Japanese Laid-open Patent Publication No.
2008-259544
[Patent Document 8] Japanese Laid-open Patent Publication No.
2009-11381
[Patent Document 9] Japanese Laid-open Patent Publication No.
2012-223435
SUMMARY OF THE INVENTION
Problem that the Invention is to Solve
Fixation is being performed for restraining eye movement during OCT
measurement. Fixation is carried out by presenting a fixation
target for causing an eye to gaze in a predetermined direction.
Many ophthalmologic imaging apparatuses are provided with an
optical system for presenting fixation targets (fixation optical
system). In ophthalmologic imaging apparatuses capable of
performing OCT measurement, part of optical path of measurement
light and part of optical path of fixation optical system are
common. For example, a common objective lens guides both
measurement light and fixation light to an eye.
When an attachment as described above is applied to such an
ophthalmologic imaging apparatus, a lens provided in the attachment
changes image-formation state of fixation light. In that case,
fixation cannot be performed properly. That is, since installation
of an attachment shifts image-formation position of fixation light,
a subject cannot recognize a fixation target clearly.
A purpose of the present invention is to provide a technology that
is capable of performing fixation properly without regard to
use/non-use of an attachment.
Means for Solving the Problem
An ophthalmologic imaging apparatus of an embodiment includes: an
optical system that splits light from a first light source into
measurement light and reference light and detects interference
light of returned light of the measurement light from an eye and
the reference light; an image forming part that forms an image
based on detection result from the optical system; and an optical
unit comprising a lens that is locatable in an optical path of the
measurement light and used for changing a focus position of the
measurement light from a first site of the eye to a second site and
a joining member that joins an optical path from a second light
source to the optical path of the measurement light, wherein the
optical unit converges light from the second light source having
been guided into the optical path of the measurement light by the
joining member on a fundus of the eye via the lens.
Effect of the Invention
According to the present invention, it is possible to perform
fixation properly without regard to use/non-use of an
attachment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram illustrating an example of a
configuration of an ophthalmologic imaging apparatus according to
an embodiment.
FIG. 2 is a schematic diagram illustrating an example of a
configuration of an ophthalmologic imaging apparatus according to
an embodiment.
FIG. 3 is a schematic block diagram illustrating an example of a
configuration of an ophthalmologic imaging apparatus according to
an embodiment.
FIG. 4 is a schematic diagram illustrating an example of a
configuration of an optical unit according to an embodiment.
FIG. 5 is a schematic diagram illustrating an example of a
configuration of an ophthalmologic imaging apparatus according to
an embodiment.
FIG. 6 is a schematic block diagram illustrating an example of a
configuration of an ophthalmologic imaging apparatus according to
an embodiment.
MODES FOR CARRYING OUT THE INVENTION
Examples of embodiments of an opthalmological imaging apparatus
according to the present invention will be described in detail with
reference to the drawings. The ophthalmologic imaging apparatus
according to an embodiment forms cross-sectional images and
three-dimensional images of eye fundus by using OCT. In the present
description, images obtained by OCT are sometimes referred to as
OCT images. Further, a measurement operation for forming OCT images
is sometimes referred to as OCT measurement. Contents described in
the documents cited in this description may be applied to the
following embodiments.
In the following embodiments, configurations in which Fourier
Domain OCT is employed will be described in detail. Particularly,
ophthalmologic imaging apparatuses according to the embodiments are
capable of obtaining both a fundus OCT image with Spectral Domain
OCT and a fundus image as the apparatus disclosed in Patent
Document 5.
By attaching an attachment (optical unit) to this opthalmological
imaging apparatus for fundus imaging, its usage is changed to
anterior-eye-part imaging. Note that it is possible to change usage
of an opthalmological imaging apparatus originally for
anterior-eye-part imaging to fundus imaging by attaching an
attachment (optical unit) to it. Imaging target sites are not
limited to fundus and anterior eye part and may be any sites of an
eye such as vitreous body or crystalline lens. Further, a
configuration may be applied in which attachments (optical units)
are prepared according to imaging target sites, respectively, and
these are selectively attached. It is possible to automatically
select use/non-use of attachments (optical units) and/or select an
attachment to be used. These selections may be executed based on
photography modes applied in the past, names of diseases, etc., for
example.
Configurations according to the present invention may be applied to
an ophthalmologic imaging apparatus of any type other than Spectral
Domain such as Swept Source OCT. Further, although a combination of
an OCT apparatus and retinal camera is described in the following
embodiments, it is possible to combine an OCT apparatus having
configurations of the present embodiment with any fundus imaging
apparatus other than retinal camera such as an SLO, slit lamp
microscope, ophthalmologic operation microscope, etc. Further,
Configurations according to the embodiments may be installed in a
single-function OCT apparatus.
First Embodiment
[Configurations]
As shown in FIG. 1 and FIG. 2, an ophthalmologic imaging apparatus
1 includes a retinal camera unit 2, an OCT unit 100, an arithmetic
and control unit 200 and an optical unit 300 as an attachment. The
retinal camera unit 2 has optical systems almost the same as a
conventional retinal camera. The OCT unit 100 is provided with
optical systems for obtaining OCT images of eye fundus. The
arithmetic and control unit 200 is provided with a computer that
executes various arithmetic processing, control processing, etc. It
is possible to insert/remove the optical unit 300 into/from an
optical path toward an eye E. The optical unit 300 is removed from
the optical path in the case of fundus OCT measurement and located
in the optical path in the case of anterior-eye-part OCT
measurement.
[Retinal Camera Unit]
The retinal camera unit 2 shown in FIG. 1 is provided with an
optical system for acquiring two-dimensional images (fundus images)
representing surface morphology of a fundus Ef of the eye E. Fundus
images include observation images, photographed images, etc. An
observation image is a monochromatic moving image formed at a
predetermined frame rate using near-infrared light, for example. A
photographed image may be a color image captured by flashing
visible light or a monochromatic still image captured by using
near-infrared light or visible light as illumination light, for
example. The retinal camera unit 2 may also be capable of capturing
other types of images such as a fluorescein angiography image,
indocyanine green angiography image and an autofluorescent
image.
The retinal camera unit 2 is provided with a chin rest and forehead
placement for supporting a subject's face. Moreover, the retinal
camera unit 2 is provided with an illumination optical system 10
and imaging optical system 30. The illumination optical system 10
irradiates illumination light to the fundus Ef. The imaging optical
system 30 guides fundus reflected light of the illumination light
to imaging devices (CCD image sensors 35, and 38 (sometimes
referred to simply as CCD)). Moreover, the imaging optical system
30 guides measurement light input from the OCT unit 100 to the
fundus Ef and guides the measurement light returned from the fundus
Ef (returned light of the measurement light from the fundus Ef) to
the OCT unit 100.
An observation light source 11 of the illumination optical system
10 includes a halogen lamp, for example. Light (observation
illumination light) output from the observation light source 11 is
reflected by a reflection mirror 12 with a curved reflection
surface, and becomes near-infrared after passing through a visible
cut filter 14 via a condenser lens 13. Further, the observation
illumination light is once converged near an imaging light source
15, reflected by a mirror 16, and passes through relay lenses 17
and 18, a diaphragm 19 and a relay lens 20. Then, the observation
illumination light is reflected on the peripheral part (the
surrounding region of an aperture part) of an aperture mirror 21,
transmitted through a dichroic mirror 46, and refracted by an
objective lens 22, thereby illuminating the fundus Ef. LED (Light
Emitting Diode) may be used as the observation light source.
Fundus reflection light of the observation illumination light is
refracted by the objective lens 22, transmitted through the
dichroic mirror 46, passes through the aperture part formed in the
center region of the aperture mirror 21, transmitted through a
dichroic mirror 55, travels through a focusing lens 31, and
reflected by a mirror 32. Further, the fundus reflection light is
transmitted through a half-mirror 39A, refracted by reflected by a
dichroic mirror 33, and forms an image on the light receiving
surface of the CCD image sensor 35 by a condenser lens 34. The CCD
image sensor 35 detects the fundus reflection light at a preset
frame rate, for example. An image (observation image) based on the
fundus reflection light detected by the CCD image sensor 35 is
displayed on a display device 3. When the imaging optical system is
focused on the anterior eye part, an observation image of the
anterior eye part of the eye E is displayed.
The imaging light source 15 includes a xenon lamp, for example. The
light (imaging illumination light) output from the imaging light
source 15 is irradiated to the fundus Ef via the same route as that
of the observation illumination light. The fundus reflection light
of the imaging illumination light is guided to the dichroic mirror
33 via the same route as that of the observation illumination
light, transmitted through the dichroic mirror 33, reflected by a
mirror 36, and forms an image on the light receiving surface of the
CCD image sensor 38 by a condenser lens 37. An image (photographed
image) based on the fundus reflection light detected by the CCD
image sensor 38 is displayed on the display device 3. The display
device 3 for displaying the observation image and the display
device 3 for displaying the photographed image may be the same or
different. Further, when similar photographing is carried out by
illuminating the eye E with infrared light, infrared photographed
image is displayed. Moreover, LED may be used as the imaging light
source.
An LCD (Liquid Crystal Display) 39 displays fixation targets,
targets for measuring visual acuity etc. A fixation target is a
visual target for fixating the eye E used for fundus photography,
OCT measurement, etc.
Part of light output from the LCD 39 is reflected by the
half-mirror 39A, reflected by the mirror 32, passes through the
focusing lens 31 and dichroic mirror 55, passes through the
aperture part of the aperture mirror 21, passes through the
dichroic mirror 46, refracted by the objective lens 22 and
projected onto the fundus Ef.
By changing display position of fixation target on the screen of
the LCD 39, fixation position of the eye E may be changed. Examples
of fixation positions of the eye E include position for acquiring
images centered at macula of the fundus Ef, position for acquiring
images centered at optic papilla, position for acquiring images
centered at fundus center located between macula and optic papilla,
etc. as in conventional retinal cameras. Display position of
fixation target may be arbitrarily changed.
The retinal camera unit 2 is provided with an alignment optical
system 50 and focus optical system 60 similarly to conventional
retinal cameras. The alignment optical system 50 generates target
(alignment target) for matching position of the optical system with
the eye E (alignment). The focus optical system 60 generates target
(split target) for focusing on the fundus Ef.
Light output from an LED 51 of the alignment optical system 50
(alignment light) passes through diaphragms 52 and 53 and a relay
lens 54, is reflected by the dichroic mirror 55, passes through the
aperture part of the aperture mirror 21, is transmitted through the
dichroic mirror 46, and is projected onto cornea of the eye E by
the objective lens 22.
Cornea reflection light of the alignment light passes through the
objective lens 22, the dichroic mirror 46 and the aperture part,
part of the cornea reflection light is transmitted through the
dichroic mirror 55, passes through the focusing lens 31, reflected
by the mirror 32, transmitted through the half-mirror 39A,
reflected by the dichroic mirror 33, and projected onto light
receiving surface of the CCD image sensor 35 by the condenser lens
34. An image (alignment target) captured by the CCD image sensor 35
is displayed on the display device 3 together with observation
image. The user may conduct alignment operation in the same way as
conventional retinal cameras. Further, alignment may be performed
in a way in which the arithmetic and control unit 200 analyzes
position of the alignment target and moves the optical system
(automatic alignment).
When performing focus adjustment, reflection surface of a
reflection rod 67 is positioned at a slanted position in the
optical path of the illumination optical system 10. Light output
from an LED 61 of the focus optical system 60 (focus light) passes
through a relay lens 62, is split into two light fluxes by a split
target plate 63, passes through a two-hole diaphragm 64, is
reflected by a mirror 65, and is reflected after an image is formed
once on the reflection surface of the reflection rod 67 by a
condenser lens 66. Further, the focus light passes through the
relay lens 20, is reflected at the aperture mirror 21, is
transmitted through the dichroic mirror 46, is refracted by the
objective lens 22, and is projected onto the fundus Ef.
Fundus reflection light of the focus light passes through the same
route as the cornea reflection light of the alignment light and is
detected by the CCD image sensor 35. An image (split target)
captured by the CCD image sensor 35 is displayed on the display
device 3 together with observation image. The arithmetic and
control unit 200 analyzes position of the split target and moves
the focusing lens 31 and the focus optical system 60 to perform
focusing as in the conventional technology (automatic focusing).
Further, focusing may be performed manually while visually
recognizing split target.
The dichroic mirror 46 splits OCT optical path from fundus
photography optical path. The dichroic mirror 46 reflects light of
wavelength band for OCT and transmits light for fundus photography.
The OCT optical path is provided with, from the OCT unit 100 in
order, a collimator lens unit 40, optical path length changing part
41, galvano scanner 42, focusing lens 43, mirror 44 and relay lens
45.
The optical path length changing part 41 may be moved in a
direction indicated by the arrow in FIG. 1, thereby changing length
of the OCT optical path. This change of optical path length may be
used for correction of optical path length in accordance with axial
length of the eye E and for adjustment of interference state. The
optical path length changing part 41 may include a corner cube and
a mechanism that moves the corner cube, for example.
The galvano scanner 42 changes travelling direction of light
(measurement light LS) travelling along the OCT optical path.
Thereby, the fundus Ef is scanned by the measurement light LS. The
galvano scanner 42 may include a galvano mirror for deflecting the
measurement light LS in the x-direction, a galvano mirror for
deflecting in the y-direction, and a mechanism for independently
driving them. Accordingly, the measurement light LS may be
deflected in arbitrary direction on the xy-plane.
[OCT Unit]
A configuration example of the OCT unit 100 is explained with
reference to FIG. 2. The OCT unit 100 is provided with an optical
system for obtaining OCT images of the fundus Ef. The optical
system includes configuration similar to conventional Spectral
Domain OCT. Specifically, the optical system has configuration that
splits low-coherence light into measurement light and reference
light, superposes the measurement light returned form the fundus Ef
and the reference light having traveled through reference optical
path to generate interference light, and detects spectral
components of the interference light. The result of detection
(detection signal) is transmitted to the arithmetic and control
unit 200.
In the case of Swept Source OCT, a wavelength-sweeping light source
is provided instead of a low-coherence light source while an
optical member for spectrally decomposing interference light is not
provided. In general, any known technology according to OCT type
may be arbitrarily applied to configuration of the OCT unit
100.
A light source unit 101 outputs broadband low-coherence light L0.
The low-coherence light L0, for example, includes near-infrared
wavelength band (about 800-900 nm) and has coherence length of
about tens of micrometer. Instead, it is possible to use
near-infrared light of invisible wavelength band for human eyes as
the low-coherence light L0 such as infrared light with center
wavelength of about 1040-1060 nm.
The light source unit 101 may include light output device such as
SLD (super luminescent diode), LED, SOA (Semiconductor Optical
Amplifier), etc.
The low-coherence light L0 output from the light source unit 101 is
guided to a fiber coupler 103 by an optical fiber 102 and split
into the measurement light LS and the reference light LR.
The reference light LR is guided to an optical attenuator 105 by an
optical fiber 104. Through any known technology, the optical
attenuator 105 is under the control of the arithmetic and control
unit 200 and automatically adjusts light amount (light intensity)
of the reference light LR guided in the optical fiber 104. The
reference light LR whose light amount has been adjusted by the
optical attenuator 105 is guided to a polarization controller 106
by the optical fiber 104. The polarization controller 106 applies
stress to the loop-form optical fiber 104 from outside to adjust
polarization state of the reference light LR guided in the optical
fiber 104, for example. Configuration of the polarization
controller 106 is not limited to this and arbitrary known
technology may be applied to it. The reference light LR whose
polarization state has been adjusted by the polarization controller
106 is guided to a fiber coupler 109.
The measurement light LS generated by the fiber coupler 103 is
guided by the optical fiber 107 and converted into a parallel light
flux by the collimator lens unit 40. Further, the measurement light
LS travels through the optical path length changing part 41,
galvano scanner 42, focusing lens 43, mirror 44 and relay lens 45,
and reaches the dichroic mirror 46. Further, the measurement light
LS is reflected by the dichroic mirror 46, refracted by the
objective lens 22 and projected to the fundus Ef. The measurement
light LS is scattered (and/or reflected) at various depth positions
of the fundus Ef. Back-scattered light (returned light) of the
measurement light LS from the fundus Ef travels along the same
route as the outward way in the opposite direction to the fiber
coupler 103, and is reached the fiber coupler 109 through an
optical fiber 108.
The fiber coupler 109 superposes the back-scattered light of the
measurement light LS and the reference light LR having passed
through the optical fiber 104. Interference light LC thus generated
is guided by an optical fiber 110 and output from an exit end 111.
Further, the interference light LC is converted into a parallel
light flux by a collimator lens 112, spectrally divided (spectrally
decomposed) by a diffraction grating 113, converged by a condenser
lens 114, and projected onto the light receiving surface of a CCD
image sensor 115. Although the diffraction grating 113 illustrated
in FIG. 2 is of transmission type, any other kind of a spectrally
decomposing element (such as reflection type) may be used.
The CCD image sensor 115 is for example a line sensor and detects
respective spectral components of the spectrally decomposed
interference light LC and converts them into electric charges. The
CCD image sensor 115 accumulates such electric charges, generates
detection signal and transmits the detection signal to the
arithmetic and control unit 200.
Although Michelson-type interferometer is employed in the present
embodiment, any type of interferometer such as a Mach-Zehnder-type
may be employed as necessary. Instead of CCD image sensor, other
types of image sensors such as CMOS (Complementary Metal Oxide
Semiconductor) image sensor may be used.
[Arithmetic and Control Unit]
Configuration of the arithmetic and control unit 200 will be
described. The arithmetic and control unit 200 analyzes detection
signals input from the CCD image sensor 115 to form OCT images of
the fundus Ef. Arithmetic processing for that may be the same as
conventional Spectral Domain OCT.
The arithmetic and control unit 200 controls each part of the
retinal camera unit 2, display device 3 and OCT unit 100. For
example, the arithmetic and control unit 200 displays OCT images of
the fundus Ef on the display device 3.
As controls for the retinal camera unit 2, the arithmetic and
control unit 200 executes controls of the observation light source
101, imaging light source 103, LED's 51 and 61, LCD 39, focusing
lenses 31 and 43, reflection rod 67, focus optical system 60,
optical path length changing part 41, galvano scanner 42, etc.
Further, as controls for the OCT unit 100, the arithmetic and
control unit 200 executes control of the light source unit 101,
optical attenuator 105, polarization controller 106, CCD image
sensor 115, etc.
The arithmetic and control unit 200 includes a microprocessor, RAM,
ROM, hard disk drive, communication interface, etc. as in
conventional computers. Storage device such as the hard disk drive
stores computer programs for controlling the ophthalmologic imaging
apparatus 1. The arithmetic and control unit 200 may be provided
with various circuit boards such as circuit boards for forming OCT
images. The arithmetic and control unit 200 may be provided with
operation devices (input devices) such as a keyboard, mouse, etc.
and/or a display device such as LCD etc.
The retinal camera unit 2, display device 3, OCT unit 100 and
arithmetic and control unit 200 may be integrally arranged (that
is, housed within a single case) or separately arranged in two or
more cases.
[Control System]
Configuration of control system of the ophthalmologic imaging
apparatus 1 will be described with reference to FIG. 3.
(Controller)
Center of control system of the ophthalmologic imaging apparatus 1
is a controller 210. The controller 210 includes the aforementioned
microprocessor, RAM, ROM, hard disk drive, communication interface,
etc., for example. The controller 210 is provided with a main
controller 211 and storage 212.
(Main Controller)
The main controller 211 performs various kinds of controls
described above. In particular, the main controller 211 controls a
focus driver 31A, optical path length changing part 41 and galvano
scanner 42 of the retinal camera unit 2 as well as the light source
unit 101, optical attenuator 105 and polarization controller 106 of
the OCT unit 100.
The focus driver 31A moves the focusing lens 31 in the optical-axis
direction. Thereby, Focus position of the imaging optical system 30
is changed. The main controller 211 may control an optical system
driver (illustration omitted) to move the optical system provided
in the retinal camera unit 2 three-dimensionally. This control is
used for alignment and tracking. Tracking is an operation for
moving the optical system in accordance with eye movement of the
eye E. In the case of performing tracking, alignment and focusing
are performed in advance. Tracking is a function of moving the
optical system so as to follow eye movement in order to maintain
suitable positional relationship in which alignment and focusing
are matched.
The main controller 211 writes data into the storage 212 and reads
out data from the storage 212.
(Storage)
The storage 212 stores various kinds of data. Data stored in the
storage 212 may include OCT image data, fundus image data, eye
information, etc. The eye information includes information on a
subject such as patient ID and name and information on an eye such
as left/right eye identification etc. The storage 212 stores
various programs and data for operating the ophthalmologic imaging
apparatus 1.
(Image Forming Part)
The image forming part 220 forms image data of a cross-sectional
image of the fundus Ef based on detection signals from the CCD
image sensor 115. This processing includes noise elimination (noise
reduction), filtering, FFT (Fast Fourier Transform), etc. similarly
to conventional Spectral Domain OCT. in the case of other types of
OCT, the image forming part 220 executes known processing according
to the type applied.
The image forming part 220 includes circuit boards described above,
for example. Note that "image data" and "image" based on the image
data may be identified with each other in the description.
(Image Processor)
An image processor 230 executes various kinds of image processing
and analysis on images formed by the image forming part 220. For
example, the image processor 230 executes various corrections such
as brightness correction, dispersion correction of images, etc. The
image processor 230 executes various kinds of image processing and
analysis on images obtained by the retinal camera unit 2 (fundus
images, anterior-eye images, etc.).
The image processor 230 executes known image processing such as
interpolation of pixels between cross-sectional images to form
three-dimensional image data of the fundus Ef. Three-dimensional
image data is image data in which of pixel positions are defined by
three-dimensional coordinate system. Examples of three-dimensional
image data include image data composed of three-dimensionally
arranged voxels. Such image data is referred to as volume data or
voxel data. In the case of displaying images based on volume data,
the image processor 230 executes rendering (volume rendering, MIP
(Maximum Intensity Projection), etc.) on volume data and forms
image data of a pseudo three-dimensional image from a preset
viewpoint. This pseudo three-dimensional image is displayed on a
display device such as a display 240A.
Stack data of multiple cross-sectional images may be formed as
three-dimensional image data. Stack data is image data obtained by
three-dimensionally arranging multiple cross-sectional images
obtained along multiple scanning lines based on positional relation
of the scanning lines. In other words, stack data is image data
obtained by expressing multiple cross-sectional images defined by
originally individual two-dimensional coordinate systems by a
single three-dimensional coordinate system (that is, obtained by
embedding cross-sectional images into a three-dimensional
space).
Such an image processor 230 includes the aforementioned
microprocessor, RAM, ROM, hard disk drive, circuit boards, etc.,
for example. Computer programs for causing the microprocessor to
perform above functions are previously stored in storage devices
such as the hard disk drive.
(User Interface)
A user interface 240 includes the display 240A and operation part
240B. The display 240A includes a display device of the arithmetic
and control unit 200 and/or the display device 3. The operation
part 240B includes manipulators of the arithmetic and control unit
200. The operation part 240B may include buttons, keys, etc.
provided on the case of the ophthalmologic imaging apparatus 1 or
outside thereof. For example, when the retinal camera unit 2 has a
case similar to conventional retinal cameras, a joy stick,
operation panel, etc. provided on the case may be included in the
operation part 240B. The display 240A may include various display
devices such as touch panel etc. provided on the case of the
retinal camera unit 2.
It is not necessary for the display 240A and operation part 240B to
be configured individually. For example, like touch panel, display
function and operation function may be integrated. In this case,
the operation part 240B includes touch panel and computer programs.
Content of operation to the operation part 240B is input into the
controller 210 as electrical signals. Operations and/or information
input may be performed by using graphical user interface (GUI)
displayed on the display 240A and the operation part 240B.
[Optical Unit]
Configuration example of the optical unit 300 is illustrated in
FIG. 4. The optical unit 300 is positioned in front of the
objective lens 22, that is, positioned between the objective lens
22 and the eye E when OCT measurement of the anterior eye part Ea
of the eye E is performed. The optical unit 300 includes a lens
(objective lens 305) for converging the measurement light LS for
OCT measurement on the anterior eye part Ea and an optical system
for projecting a fixation target onto the fundus Ef.
As another example, in the case in which an optical unit is
attached to an ophthalmologic imaging apparatus for cornea
(anterior eye part), this optical system is removed from the
optical path in the case of corneal OCT measurement and located in
the optical path in the case of fundus OCT measurement. This
optical unit includes a lens for converging measurement light on
the fundus and an optical system for projecting a fixation target
onto the fundus.
In the present example, a light source (fixation light source 310)
for generating fixation target is arranged outside the optical unit
300. A fixation light source may be arranged inside an optical
unit. In all cases, a fixation light source may be dedicated to
fixation or may also be used for other functions. A fixation light
source outputs at least visible light, for example.
When a fixation light source is provided outside an optical unit,
the fixation light source is used for projecting internal fixation
targets in the case of corneal OCT measurement and used as an
external fixation light source in the case of fundus OCT
measurement, for example. The fixation light source may have
arbitrary functions other than external fixation light source such
as a function for projecting patterns for measuring corneal
shape.
FIG. 5 illustrates an example of the case in which an external
fixation light source for performing peripheral fixation in fundus
OCT measurement is provided. Peripheral fixation is a kind of
fixation for carrying out OCT measurement of peripheral area of
fundus. FIG. 5 shows a schematic view of a front face (face on the
eye E side) of the retinal camera unit 2 (the case thereof). The
objective lens 22 is arranged on the front face of the retinal
camera unit 2. The objective lens 22 is housed in a lens-barrel
22A. A light-source holder 23 is provided around the lens-barrel
22A. A plurality of external fixation light sources 24i (i=1 to n)
for peripheral fixation are provided in the light-source holder 23.
Each external fixation light source 24i is an LED, for example. In
the present example, the plurality of external fixation light
sources 24i are arranged on a circle centered at the optical axis
of the objective lens 22 at equal intervals. The controller 210
controls the fixation light sources 24i (turning on/off, blinking,
changing output light amount, changing output wavelength,
etc.).
The optical unit 300 is arranged on the front face of the retinal
camera unit 2. Light output from any of the fixation light sources
24i (one located at highest position, for example) is used as light
output from the fixation light source 310 shown in FIG. 4.
In the case in which a fixation light source is arranged inside an
optical unit and the optical unit may be removed from the optical
path while being connected to the ophthalmologic imaging apparatus,
light from the fixation light source may be guided to the outside
of the optical unit by means of light guiding means such as an
optical fiber, thereby using this light as other usages (external
fixation light source etc.).
An example shown in FIG. 4 is described. The optical unit 300 of
the present example includes a relay lens 301, reflection mirror
302, relay lens 303, beam splitter 304 and objective lens 305.
Light output from the fixation light source 310 and entered in the
optical unit 300 (fixation light LF) is guided to the relay lens
301. The relay lenses 301 and 303 function as an optical system for
relaying an image of the fixation light source 310 to the beam
splitter 304. More specifically, the fixation light LF becomes a
parallel light flux through the relay lens 301, is reflected by the
reflection mirror 302, and converged on a reflection surface of the
beam splitter 304 by the relay lens 303.
The beam splitter 304 is arranged at a location conjugate to the
fundus Ef, for example. The beam splitter 304 joins optical path of
the fixation light LF and optical path of the measurement light LS.
The beam splitter 304 is a dichroic mirror that reflects visible
light (fixation light LF) and transmits infrared light (measurement
light LS), for example. Alternatively, the beam splitter 304 may be
a half mirror.
The fixation light LF transmitted the beam splitter 304 is
converged (that is, forms an image) on the fundus Ef by the
objective lens 305 and eyeball optical system of the eye E.
Accordingly, an fixation target based on the fixation light source
310 is projected on the fundus Ef.
On the other hand, the measurement light LS passes through the
objective lens 22 of the retinal camera unit 2, passes through the
beam splitter 304 of the optical unit 300, and is converged on the
cornea Ec by the objective lens 305.
[Effects]
Effects of the ophthalmologic imaging apparatus 1 are
explained.
The ophthalmologic imaging apparatus 1 includes an optical system,
image forming part and optical unit. The optical system splits
light from a first light source (light source unit 101, for
example) into measurement light and reference light and detects
interference light of returned light of the measurement light from
an eye and the reference light. The image forming part (image
forming part 220, for example) forms an image based on detection
result from the optical system (detection signals generated by the
CCD image sensor 115, for example).
The optical unit (optical unit 300, for example) is locatable in an
optical path of the measurement light. The optical unit includes a
lens that is used for changing a focus position of the measurement
light from a first site of the eye to a second site. A combination
of the first and second sites is arbitrary. For example, the first
site is a fundus and the second site is an anterior eye part (such
as cornea). Alternatively, the first site is an anterior eye part
(such as cornea) and the second site is a fundus. Further, the
optical unit includes a joining member that joins an optical path
from a second light source (fixation light source) to the optical
path of the measurement light. The joining member may be a beam
splitter of any type (dichroic mirror 304, half mirror, etc., for
example). The joining member of the optical unit converges light
from the second light source having been guided into the optical
path of the measurement light on a fundus of the eye via the
lens.
According to the ophthalmologic imaging apparatus thus configured,
light from the second light source may be converged on the fundus
through the optical unit when the optical unit is applied.
Therefore, the subject is capable of visually recognizing fixation
target clearly even if position of convergence (position of
image-formation) of a fixation light flux from an optical system
that is a different system from the optical unit is shifted from a
retina due to the use of the optical unit. Accordingly, it is
possible to perform fixation properly without regard to use/non-use
of the optical unit. Note that the second light source may be an
LED, flat panel display (such as LCD etc.).
The first light source may output light including infrared light
and the second light source may output light including visible
light. In this case, the joining member may include a dichroic
mirror (dichroic mirror 305, for example).
The second light source may be provided in the optical unit. That
is, the optical unit may project fixation target on the fundus
based on the light from the second light source provided therein.
According to such a configuration, although the second light source
is required to be provided in the optical unit, configurations for
guiding light from a light source previously provided in the
ophthalmologic imaging apparatus to the optical unit are not
required.
The second light source may be provided outside the optical unit.
That is, the optical unit may project fixation target on the fundus
based on the light from the second light source provided thereout.
According to such a configuration, it is possible to utilize a
light source previously provided in the ophthalmologic imaging
apparatus (this light source may have a function other than
fixation) as the second light source for projecting fixation target
on the fundus when using the optical unit. Accordingly,
simplification of configuration of the optical unit may be
advanced.
When the second light source is provided outside the optical unit,
any of the following configurations may be adopted. Firstly, the
optical system may include an objective lens (objective lens 22,
for example) and one or more light sources arranged around the
objective lens (external fixation light sources 24i, for example).
Further, the second light source may include any of the one or more
light sources. In such a configuration, any of light sources
provided outside the optical unit and provided around the objective
lens of the optical system for OCT measurement are used as the
second light source for projecting fixation target on the fundus
when using the optical unit.
When the opthalmological imaging apparatus includes one or more
external fixation light sources (external fixation light sources
24i, for example), the second light source may include any of the
one or more external fixation light sources
The optical unit may include a relay optical system that relays an
image of the second light source to the joining member. According
to such a configuration, simplification of configuration of the
optical unit may be advanced. In the case of adopting this
configuration, the second light source may be a substantial point
source of light.
Second Embodiment
The present embodiment describes switching control of means for
fixation between use and non-use of an attachment (optical unit).
Hereinafter, symbols used in the first embodiment are applied.
[Configuration]
Configuration of optical system of an ophthalmologic apparatus of
the present embodiment may be the same as that of the first
embodiment (see FIGS. 1, 2 and 5). Further, an optical unit
(attachment) may be the same as that of the first embodiment (see
FIG. 4).
A control system of the ophthalmologic apparatus of the present
embodiment has a configuration illustrated in FIG. 6, for example.
Difference from the control system of the first embodiment (FIG. 3)
is presence of a detector 250 and clear indication of the external
fixation light sources 24i.
The external fixation light sources 24i correspond to fixation
light source (second light source) provided outside the optical
unit 300. As described in the first embodiment, the fixation light
source provided outside the optical unit 300 is not limited to
external fixation light source. On the other hand, when fixation
light source is provided inside the optical unit 300, the
controller 210 controls this fixation light source (turning on/off,
blinking, changing output light amount, changing output wavelength,
etc.).
The detector 250 detects whether or not the optical unit 300 is
located in the optical path of the measurement light LS. The
detection means one or both of detection of an event that the
optical unit 300 is located in the optical path and detection of an
event that the optical unit 300 is not located in the optical path.
The detector 250 includes a micro switch, position sensor, etc.,
for example.
When a micro switch is employed, the micro switch is arranged at a
location contacting with the optical unit 300 arranged in the
optical path of the measurement light LS, for example. This micro
switch is turned on when the optical unit 300 is located in the
optical path of the measurement light LS and turned off when it is
removed from the optical path. This micro switch inputs signals to
the controller 210 when it is "on". The controller 210 recognizes
whether or not the optical unit 300 is located in the optical path
by presence/absence of such signals.
When a position sensor is employed, the position sensor detects
current position of the optical unit 300 and inputs signals
indicating detection result to controller 210, for example. The
controller 210 recognizes whether or not the optical unit 300 is
located in the optical path based on contents of such signals.
As in the first embodiment, a fixation optical system for
presenting a fixation target to the eye E is installed in the
ophthalmologic apparatus of the present embodiment. This fixation
optical system may include the LCD 39. Light output from the LCD 39
is reflected by the half-mirror 39A, reflected by the mirror 32,
passes through the focusing lens 31 and dichroic mirror 55, passes
through the aperture part of the aperture mirror 21, passes through
the dichroic mirror 46, refracted by the objective lens 22 and
converged on the fundus Ef. When the optical unit 300 is located in
front of the objective lens 22, the subject cannot visually
recognize fixation target clearly because the LCD 39 and the cornea
Ec are conjugate to each other.
Operations executed by the controller 210 are explained. Upon
recognizing that the optical unit 300 is located in the optical
path of the measurement light LS, the controller 210 executes
control for converging light from the external fixation light
source 24i by means of the optical unit 300. This control includes
at least turning on the external fixation light source 24i. In the
case in which LCD 39 is outputting light at the time of recognizing
that the optical unit 300 is located in the optical path of the
measurement light LS, the controller 210 turns off the LCD 39.
On the other hand, upon recognizing that the optical unit 300 is
not located in the optical path of the measurement light LS, the
controller 210 executes control for presenting fixation target by
the fixation optical system installed in the ophthalmologic imaging
apparatus. This control includes at least control of the LCD 39 to
display fixation target. In the case in which the external fixation
light source 24i is outputting light at the time of recognizing
that the optical unit 300 is not located in the optical path of the
measurement light LS, the controller 210 turns off the external
fixation light source 24i.
[Effects]
Effects of the ophthalmologic imaging apparatus of the present
embodiment are explained.
The ophthalmologic imaging apparatus of the present embodiment
provides the same effects as the first embodiment.
In addition, the ophthalmologic imaging apparatus of the present
embodiment may execute control for converging light from the second
light source (external fixation light source 24i, for example) on
the fundus by means of the optical unit (optical unit 300, for
example) when the optical unit is used. Therefore, manual operation
is not required for switching means for fixation at the time of use
of the optical unit (at the time of transferring from fundus OCT
measurement to anterior-eye-part OCT measurement, for example).
Further, the ophthalmologic imaging apparatus of the present
embodiment may execute control for presenting fixation target by
the fixation optical system provided in the ophthalmologic imaging
apparatus when the optical unit is not used. Therefore, manual
operation is not required for switching means for fixation at the
time of non-use of the optical unit (at the time of transferring
from anterior-eye-part OCT measurement to fundus OCT measurement,
for example).
In this way, according to the ophthalmologic imaging apparatus of
the present embodiment, it is possible to improve operability at
the time of setting or switching target site of OCT
measurement.
Configuration of the detector is not limited to that detecting
position or action of the optical unit. For example, the detector
may detect use/non-use of the optical system based on information
input from outside. Specifically, the detector may recognize
use/non-use of the optical system before inserting or removing the
optical unit into or from the optical path based on content of
examination input by the user (explicit or implicit indication of
measurement target site, for example). Alternatively, it is
possible to recognize use/non-use of the optical system by
referring to electric medical record of a concerned subject (such
as content of examination), for example.
<Optical Unit>
The optical units described in the above embodiments are attachable
to an ophthalmologic imaging apparatus having OCT function. This
ophthalmologic imaging apparatus includes an optical system and
image forming part. The optical system splits light from a first
light source into measurement light and reference light and detects
interference light of returned light of the measurement light from
an eye and the reference light. The image forming part forms an
image based on detection result from the optical system.
The optical unit is locatable in an optical path of the measurement
light. Further, the optical unit includes a lens that is used for
changing a focus position of the measurement light from a first
site of the eye to a second site and a joining member that joins an
optical path from a second light source to the optical path of the
measurement light. In addition, the optical unit is configured to
converge light from the second light source having been guided into
the optical path of the measurement light by the joining member on
a fundus of the eye via the lens. The second light source is
provided inside or outside the optical unit.
The first light source may output light including infrared light,
the second light source may output light including visible light,
and the joining member may include a dichroic mirror. The optical
unit may include a relay optical system that relays an image of the
second light source to the joining member.
According to the optical unit thus configured, it is possible to
perform fixation properly without regard to use/non-use of the
optical unit.
Modification Examples
Configurations described above are merely illustrations for
implementing the present invention. Therefore, it is possible to
make arbitrary modification (omission, replacement, addition, etc.)
within the scope of the present invention.
In the above embodiments, projecting position of fixation target by
the optical unit 300 may be changeable. For example, it is possible
to apply a configuration in which projecting position of fixation
target is changed by replacing the reflection mirror 302 in the
optical unit 300 with a deflecting mirror. The deflecting mirror
may be a two-dimensional deflecting mirror such as a dual-axis
galvano mirror and operated by receiving control from the
controller 210. As another configuration for changing projecting
position of fixation target, a mechanism that moves the beam
splitter 304 may be provided. This mechanism moves the beam
splitter 304 along a normal direction of functioning face of the
beam splitter 304 (face having a function joining/splitting optical
paths, face having filtering function, etc.). This mechanism is
operated by receiving control from the controller 210. According to
the present example, since fixation position of the eye E may be
changed when performing anterior-eye-part OCT measurement, it is
possible to facilitate OCT measurement of arbitrary site of cornea
(such as peripheral site).
In the above embodiments, focus adjustment of fixation target
projected on the fundus Ef by the optical unit 300 may be
performed. For example, focus adjustment of fixation target may be
realized by providing a mechanism that moves the relay lens 303
(and/or the reflection mirror 302) in the optical unit 300 along
the optical-axis direction. This mechanism is operated by receiving
control from the controller 210. As an example of this control, the
ophthalmologic imaging apparatus 1 may analyze an image (such as
observation image) of the eye E acquired in real time to obtain
projection state (focus state) of fixation target, and control the
mechanism according to the projection state. Alternatively, the
ophthalmologic imaging apparatus 1 may display a real-time image of
the fundus Ef on which fixation target is being projected, and
control the mechanism according to manual operation performed by
the user based on the displayed image. According to the present
example, it is possible to present, to the eye E, suitable fixation
target whose focus is matched.
The optical units 300 described in the above embodiments are merely
example. For example, regarding arrangement of optical elements,
the beam splitter 304 is not necessarily arranged at a position of
pupil conjugate.
In the above embodiments, optical path length difference between
optical paths of measurement light LS and reference light LR is
changed by varying position of the optical path length changing
part 41; however, a method of changing optical path length
difference is not limited to this. For example, it is possible to
change optical path length difference by providing a reflection
mirror (reference mirror) in optical path of reference light and
moving the reference mirror in the advancing direction of the
reference light to change the optical path length of the reference
light. Further, optical path length difference may be changed by
moving the retinal camera unit 2 and/or OCT unit 100 with respect
to the eye E to change the optical path length of the measurement
light LS. Moreover, in the case in which an object is not a living
tissue or the like, it is possible to change optical path length
difference by moving the object in the depth direction
(z-direction).
Computer programs for implementing the above embodiments can be
stored in any kind of recording medium readable by computers. As
such recording media, for example, an optical disk, a semiconductor
memory, a magneto-optic disk (CD-ROM, DVD-RAM, DVD-ROM, MO, and so
on), and a magnetic storage (a hard disk, a Floppy Disk.TM., ZIP,
and so on) can be used.
In addition, it is possible to transmit/receive such programs
through networks such as internet, LAN etc.
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